Ring diameter 19 mm
Updated: 14 July 2026
An inside diameter of 19 mm matches European ring size 60 in this chart. 19 mm times 3.1416 is about 59.7 mm inside circumference, and in Europe that circumference in millimeters is the size. The closest row in the chart is 60 with 19.1 mm diameter.
19 mm in the chart
| Size (circumference) | Diameter | US | UK |
|---|---|---|---|
| 58 mm | 18.5 mm | US 8.5 | UK Q |
| 59 mm | 18.8 mm | US 9 | UK R |
| 60 mm | 19.1 mm | US 9 | UK S |
| 61 mm | 19.4 mm | US 9.5 | UK T |
| 62 mm | 19.7 mm | US 10 | UK T |
From diameter to size
The size is the inside circumference, but what you usually measure is the inside diameter. Pi connects the two:
- Multiply the diameter by 3.1416. 19 mm times 3.1416 is 59.7 mm.
- That result is the circumference, which is the European size.
- Round to the nearest whole size. Here that is 60.
Measure the diameter from inside edge to inside edge, not across the band. Half a millimeter off ends up as one or two sizes.
How to measure properly
These are the reliable ways to measure:
- Take a ring that already fits the right finger, lay it on a ruler and measure the inside diameter from edge to edge.
- Or use a ring sizer, a set of sample rings you try on one by one.
- Or have a jeweler measure your finger.
The string method (wrap a string around the finger and measure its length) is a fallback for when none of the above is possible. It gives you a rough estimate. Measure the finger you want to wear the ring on and remember that the ring also has to pass your knuckle.
The values either side
18 mm diameter is size 57, 20 mm is size 63. One millimeter of diameter is a good three millimeters of circumference, so about three sizes. That is why it pays to measure twice.
Common questions
What ring size is 19 mm diameter?
Size 60. 19 mm times 3.1416 is about 59.7 mm inside circumference, and the circumference is the European size.
How do I convert diameter into circumference?
Multiply the diameter by 3.1416. 19 mm becomes 59.7 mm of circumference.
What is 19 mm diameter in US sizes?
That is about US 9 and UK S.